I'm uploading files using the ASP.NET Web API. I've done this before the RC but for some reason the file is being saved as "BodyPart_3ded2bfb-40be-4183-b789-9301f93e90af" instead of the file name. The filename variable below returns this bodypart string too instead of the file name. I can't seem to figure out where I'm going wrong. Any help is appreciated.

That was a concious change we made -- it was considered a security risk to take the file name provided in the Content-Disposition header field and so instead we now compute a file name which is what you are seeing.

If you want to control the server local file name yourself then you can derive from MultipartFormDataStreamProvider and override GetLocalFileName to provide whatever name you want. Note though that there may be security considerations doing so.